JP2004343899A - Power supply device for plasma generation and exhaust gas purification system - Google Patents

Abstract

Provided are a power supply device capable of applying a required high voltage to a plurality of plasma generators and an exhaust gas purification system that can be configured at low cost and compactly.
A plasma generating power supply device is for applying a high voltage to each of a plurality of plasma reactors and includes a first transformer and a second transformer. The primary coil of the first transformer 33 is connected to the primary power supply 31 via the inverter circuit 32 controlled by the controller 35, and the secondary coil of the transformer 33 is connected to the first plasma reactor 10. The primary coil of the second transformer 38 is connected to the secondary coil of the first transformer 33, and the secondary coil of the transformer 38 is connected to the second plasma reactor 20.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power supply device for plasma generation and an exhaust gas purification system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique of purifying exhaust gas of an internal combustion engine using a plasma generator (plasma reactor) that applies an AC voltage or a DC pulse voltage to a pair of electrodes to generate plasma between the electrodes has been known (for example, And Patent Document 1.). Such a plasma generator is usually provided with one high-voltage power supply capable of generating an AC voltage or a DC pulse voltage.
[0003]
[Patent Document 1]
JP 2001-314748 A
[Problems to be solved by the invention]
On the other hand, in recent years, an exhaust gas purification system including a plurality of plasma generators that perform different processes has been studied. In such an exhaust gas purification system, if one high-voltage power supply is provided for each plasma generator, the cost of the entire system is increased and the space efficiency of the system is deteriorated.
[0005]
Therefore, an object of the present invention is to provide a power supply device for plasma generation that can apply a required high voltage to each of a plurality of plasma generation devices, and an exhaust gas purification system that can be configured at low cost and compactly. And
[0006]
[Means for Solving the Problems]
A power supply for plasma generation according to the present invention is a power supply for plasma generation for applying a high voltage to each of a plurality of plasma generators, comprising a primary power supply, a primary coil connected to the primary power supply, and a plurality of plasmas. A first transformer including a secondary coil connected to any of the generators, an inverter circuit provided between the primary power supply and the first transformer, and a controller for generating a drive signal for operating the inverter circuit; , A primary coil connected to the secondary coil of the first transformer, and a second transformer including a secondary coil integrally connected to any one of the plurality of plasma generators.
[0007]
According to the power supply device for plasma generation of the present invention configured as described above, it becomes possible to apply a required high voltage to each of the plurality of plasma generation devices by itself. Therefore, by using the power supply device for plasma generation, it is possible to easily achieve low cost and compactness of an exhaust gas purification system including a plurality of plasma generation devices.
[0008]
In this case, it is preferable to further include a rectifier provided between the first transformer and the second transformer and a rectifier provided between the second transformer and the plasma generator.
[0009]
By employing such a configuration, a single plasma generating power supply can apply a desired high voltage to both an AC power supply type plasma generator and a DC pulse power supply type plasma generator. It becomes.
[0010]
An exhaust gas purifying system according to the present invention is an exhaust gas purifying system for purifying exhaust gas by using plasma, wherein a first plasma generation for treating exhaust gas using plasma generated by applying a high voltage to a pair of electrodes. An apparatus, a second plasma generator for processing exhaust gas using plasma generated by applying a high voltage to a pair of electrodes, and a high voltage to each of the first and second plasma generators And a first transformer including a primary power supply, a primary coil connected to the primary power supply, and a secondary coil connected to the first plasma generator, and a primary power supply. An inverter circuit provided between the power supply and the first transformer; a controller for generating a drive signal for operating the inverter circuit; Characterized in that it comprises a second transformer comprising a secondary coil connected to the primary coil and the second plasma generating device connected to Le.
[0011]
In this exhaust gas purification system, a required high voltage is applied to each of the plurality of plasma generators by one power supply device for plasma generation. Therefore, in this exhaust gas purification system, it is not necessary to provide one high-voltage power supply device for each plasma generator, so that the cost and size of the entire system can be easily reduced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a plasma generation power supply device and an exhaust gas purification system according to the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a schematic configuration diagram showing an exhaust gas purification system according to the present invention. The exhaust gas purification system 1 shown in FIG. 1 is suitable for being applied to a vehicle, and purifies exhaust gas discharged from a combustion chamber of an internal combustion engine (for example, a diesel engine) (not shown). Built into the exhaust system. The exhaust gas purification system 1 includes a first plasma reactor 10 and a second plasma reactor 20 that are incorporated between exhaust pipes L1 and L2 that constitute an exhaust system of an internal combustion engine. In the present embodiment, the first plasma reactor 10 and the second plasma reactor 20 disposed downstream of the first plasma reactor 10 in the flow direction of the exhaust gas have different driving methods, and perform different exhaust gas treatments. .
[0014]
The first plasma reactor 10 is configured as an AC power source type plasma generator, and includes a purification vessel 11 formed of a conductive material in a substantially cylindrical shape. As shown in FIG. 1, one end of the purification vessel 11 is connected to an exhaust pipe L1 connected to the combustion chamber of the internal combustion engine, and inside the purification vessel 11 as shown by a white arrow in FIG. The exhaust gas of the internal combustion engine is introduced. A cell 12 made of a honeycomb material or the like is disposed inside the purification container 11, and a discharge electrode 14 in the form of a small-diameter rod is disposed on the longitudinal axis of the purification container 11.
[0015]
In the present embodiment, the purification vessel 11 itself is used as an anode, and the discharge electrode 14 is used as a cathode. A high AC voltage is applied to the purification vessel 11 and the discharge electrode 14. As a result, plasma can be generated between the discharge electrode 14 and the purification vessel 11 as a receiving electrode, and the particulate matter (PM) and the like contained in the exhaust gas can be removed using the energy of the generated plasma. It can be collected in the cell 12.
[0016]
On the other hand, the second plasma reactor 20 is configured as a plasma generator of a DC pulse power supply system, and has a purification vessel 21 formed of a conductive material in a substantially cylindrical shape. One end of the purification vessel 21 is connected to the downstream end of the purification vessel 11 of the first plasma reactor 10 via the connection pipe Lc, and has passed through the purification vessel 11 of the first plasma reactor 10 inside the purification vessel 21. Fluid is introduced. The other end of the purification vessel 21 is connected to an exhaust pipe L2 that forms an exhaust system together with the exhaust pipe L1, and the fluid purified in the purification vessel 21 is discharged to the outside via the exhaust pipe L2. .
[0017]
As shown in FIG. 1, a support member 22 formed in a substantially cylindrical shape by an insulator is fixed inside the purification container 21, and mesh electrodes 23A and 23C are provided at both ends of the support member 22. Has been fixed. Further, a catalyst carrier 24 is disposed inside the support member 22 and between the electrodes 23A and 23C. In the present embodiment, as the catalyst carrier 24, a carrier in which an alumina catalyst is supported on a honeycomb material made of ceramic or the like is used. Note that the catalyst carrier 24 inside the support member 22 may be omitted, and a honeycomb material or the like not carrying a catalyst may be arranged inside the support member 22. Further, any catalyst can be used as the catalyst supported on the honeycomb material or the like.
[0018]
Terminals (not shown) are connected to the electrodes 23A and 23C disposed inside the purification vessel 21, respectively. For example, the upstream electrode 23A serves as an anode and the downstream electrode 23C serves as an anode. A DC pulse voltage is applied so as to serve as a cathode. As a result, plasma can be generated between the electrodes 23A and 23C, and components such as HC, CO, NOx, and particulate matter contained in exhaust gas from the internal combustion engine are utilized by utilizing the energy of the generated plasma. It can be purified by reacting with oxygen in exhaust gas, or can be ignited and incinerated.
[0019]
A high voltage is supplied from one plasma generation power supply 30 to each of the first plasma reactor 10 and the second plasma reactor 20 configured as described above. The power supply device 30 includes a primary power supply (DC power supply) 31, an inverter circuit 32, a first transformer 33, and a first switch 34, as shown in FIG. In this embodiment, an auxiliary battery of the vehicle is used as the primary power supply 31, and the primary power supply 31 is connected to the primary coil of the first transformer 33 via the inverter circuit 32. Further, the secondary coil of the first transformer 33 is connected to the purification vessel (receiving electrode) 11 and the discharge electrode 14 of the first plasma reactor 10 via the first changeover switch 34. The first changeover switch 34 is turned on / off by a controller 35.
[0020]
As shown in FIG. 1, an inverter circuit 32 provided between the primary power supply 31 and the first transformer 33 protects the four transistors Tr1, Tr2, Tr3 and Tr4, and the transistors Tr1 to Tr4. , A flyback type full bridge circuit having diodes D1, D2, D3, and D4. A gate signal (drive signal) is provided from the controller 35 to each of the transistors Tr1 to Tr4 of the inverter circuit 32.
[0021]
The primary coil of the second transformer 38 is connected to the secondary coil of the first transformer 33 via the second switch 36 and the diode 37. Like the first switch 34, the second switch 36 is on / off controlled by the controller 35. The secondary coil of the second transformer 38 is connected to the electrodes 23A and 23C of the second plasma reactor 20 via the diode 39.
[0022]
The controller 35 has a CPU, a ROM, a RAM, an input / output port, a storage device, and the like (not shown). The controller 35 generates a gate signal to the inverter circuit 32 based on various parameters and the like obtained from the exhaust system of the internal combustion engine and the like, while following a predetermined control program and the like. The on / off control of the 2 changeover switch 36 is performed.
[0023]
Next, with reference to FIG. 2, the operation of the plasma generating power supply device 30 included in the above-described exhaust gas purification system 1 will be described.
[0024]
When the AC power supply type first plasma reactor 10 and the DC pulse power supply type second plasma reactor 20 are operated by the power supply device 30 of the exhaust gas purification system 1, the transistors Tr <b> 1 to Tr <b> 1 constituting the inverter circuit 32 are controlled by the controller 35. Gate signals Q1 to Q4 as shown in FIG. 2 are applied to Tr4. In the present embodiment, the frequency f of the gate signals Q1 to Q4 is the same, but the phase differs between the gate signals Q1 and Q4 for the transistors Tr1 and Tr4 and the gate signals Q2 and Q3 for the transistors Tr2 and Tr3 by 180 degrees. ing.
[0025]
When the gate signals Q1 to Q4 as described above are given to the transistors Tr1 to Tr4, the primary coil of the first transformer 33 connected to the primary power supply 31 via the inverter circuit 32 has a configuration as shown in FIG. A primary voltage (AC voltage) Vp1 is applied, and a primary current Ip1 flows. As a result, a boosted secondary voltage (AC voltage) Vs1 and a secondary current Is1 are induced in the secondary coil of the first transformer 33, as shown in FIG.
[0026]
Then, as shown in FIG. 2, the controller 35 controls the first changeover switch 34 between the first transformer 33 and the first plasma reactor 10 to reduce the frequency of the gate signal to the transistors Tr1 to Tr4 by half the frequency. An (f / 2) ON signal SW1 is given. As a result, an AC voltage AV1 as shown in FIG. 2 is applied to the first plasma reactor 10, and plasma is generated between the discharge electrode 14 of the first plasma reactor 10 and the purification vessel 11 as a receiving electrode. It is possible to do.
[0027]
On the other hand, the controller 35 supplies the second changeover switch 36 between the first transformer 33 and the second transformer 38 with a half frequency of the gate signal to the transistors Tr1 to Tr4 (see FIG. 2). f / 2), and an ON signal SW2 having a phase different from that of the ON signal SW1 for the first changeover switch 180 by 180 degrees. The current flowing from the secondary coil of the first transformer 33 to the second transformer 38 is rectified by the diode 37. Accordingly, a primary voltage (AC voltage) Vp2 as shown in FIG. 2 is applied to the primary coil of the second transformer 38, and a primary current Ip2 flows.
[0028]
Then, the secondary current Is2 induced in the secondary coil of the second transformer 38 is rectified by the diode 39, and the secondary coil of the second transformer 38 has a unipolar secondary voltage as shown in FIG. (DC pulse voltage) Vs2 is induced. As a result, the DC pulse voltage Vs2 boosted by the second transformer 38 is applied to the second plasma reactor 20, and plasma can be generated between the electrodes 23A and 23C of the second plasma reactor 20.
[0029]
As described above, according to the plasma generating power supply device 30 of the present invention, the required AC voltage is applied to the first plasma reactor 10 and the required AC voltage is applied to the second plasma reactor 20 by itself. DC pulse voltage can be applied. That is, in the exhaust gas purification system 1, a required high voltage is applied to the plurality of plasma reactors 10 and 20 by one power supply device 30 for plasma generation.
[0030]
Therefore, if the power supply device 30 for plasma generation is used, the cost reduction and compactness of the exhaust gas purification system 1 including the plurality of plasma reactors 10 and 20 can be easily achieved. In other words, in the exhaust gas purification system 1, since it is not necessary to provide one high-voltage power supply for each of the plasma reactors 10 and 20, the cost of the entire system can be reduced, and the entire system can be made compact to produce a vehicle. Can be improved.
[0031]
As can be seen from FIG. 2, in the present embodiment, the ON signal SW1 for the first changeover switch 34 and the ON signal SW2 for the second changeover switch 36 are one half of the gate signal for the transistors Tr1 to Tr4. Since it has the frequency (f / 2) and the phases of the two are different by 180 degrees, a high voltage is not applied to the first plasma reactor 10 and the second plasma reactor 20 at the same time.
[0032]
Further, in the above-described exhaust gas purification system 1, a diode (rectifying means) 37 is provided between the first transformer 33 and the second transformer 38, and a diode (rectifying means) is provided between the second transformer 38 and the second plasma reactor 20. Means 39 is provided to generate both an AC voltage and a DC pulse voltage in the plasma generating power supply device 30, but the present invention is not limited to this.
[0033]
That is, by omitting the diodes 37 and 39, the AC voltage required for each of the plurality of plasma reactors may be supplied from the plasma generation power supply device 30. Further, by appropriately providing a diode as a rectifier on the first transformer 33 side in addition to the diodes 37 and 39, the DC pulse voltage required for each of the plurality of plasma reactors from the plasma generation power supply 30 can be obtained. May be supplied.
[0034]
【The invention's effect】
As described above, according to the present invention, a plasma generation power supply device capable of applying a required high voltage to each of a plurality of plasma generation devices, and a low-cost and compact configuration can be achieved. An exhaust gas purification system can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an exhaust gas purification system according to the present invention.
FIG. 2 is a timing chart for explaining the operation of a power supply device for plasma generation included in the exhaust gas purification system of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exhaust gas purification system 10 First plasma reactor 11, 21 Purification container 14 Discharge electrode 20 Second plasma reactor 23A, 23C Electrode 30 Plasma generation power supply 31 Primary power supply 32 Inverter circuit 33 First transformer 34 First switch 35 Controller 36 Second changeover switches 37, 39 Diode 38 Second transformer D1, D2, D3, D4 Diode L1, L2 Exhaust pipe Tr1, Tr2, Tr3, Tr4 Transistor

Claims (3)

A power supply for plasma generation for applying a high voltage to each of the plurality of plasma generators,
A primary power supply,
A first transformer including a primary coil connected to the primary power supply and a secondary coil integrally connected to any of the plurality of plasma generators;
An inverter circuit provided between the primary power supply and the first transformer;
A controller for generating a drive signal for operating the inverter circuit;
A power supply device for plasma generation, comprising: a primary coil connected to a secondary coil of the first transformer; and a second transformer including a secondary coil integrally connected to any one of the plurality of plasma generators. . 2. A rectifier provided between the first transformer and the second transformer, and a rectifier provided between the second transformer and the plasma generator. The power supply device for plasma generation according to item 1. An exhaust gas purification system that purifies exhaust gas using plasma,
A first plasma generator for processing exhaust gas using plasma generated by applying a high voltage to a pair of electrodes,
A second plasma generator that treats exhaust gas using plasma generated by applying a high voltage to a pair of electrodes,
A plasma generation power supply for applying a high voltage to each of the first and second plasma generators;
The plasma generating power supply device,
A primary power supply,
A first transformer including a primary coil connected to the primary power supply and a secondary coil connected to the first plasma generator;
An inverter circuit provided between the primary power supply and the first transformer;
A controller for generating a drive signal for operating the inverter circuit;
An exhaust gas purification system comprising: a primary coil connected to a secondary coil of the first transformer; and a second transformer including a secondary coil connected to the second plasma generator.

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